Three inch double toilet?

[Dan WZ]

Hello,

I am remodeling a bathroom and I have 3” PVC for the toilets and main line. It runs across under the joists and the toilets etc. run with or in between the joists. My line ends with a toilet that drops into a 90 and has a 3x3x1.5 next in line to catch a sink. I need to add the toilet to the end of the line. I can do this with two long 90’s but it will be tight.

If you look at the picture the new toilet will be coming out from the left side directly opposite the current end toilet. I only have one 16” joist cavity to work with.

My question is - is it ok by code and should I use a 3” three way 45 degree horizontally?https://www.homedepot.com/p/NIBCO-3-in-PVC-DWV-45-Degree-H-x-H-x-H-Double-Wye-C48343/205799566

Thanks

 

[Tuttles Revenge]

I believe all toilet manufactures recommend installing back to back toilets using a double wye fitting and specifically state not to use double sanitary tees.

 

[Sponsor]

 

[Dan WZ]

I believe all toilet manufactures recommend installing back to back toilets using a double wye fitting and specifically state not to use double sanitary tees.

Thank you. So can I lay the double wye horizontally?

 

[Tuttles Revenge]

A horizontal double wye is a sticking point for some people. Since each side technically can not have grade if the other does, no.. however the realistic approach is to slightly grade the Street 45 so that each side does in fact have grade, just not on a teeny tiny section.. Your local inspector would have to make that call.

Below is some reasoning behind that.

https://www.kingcounty.gov/depts/he...cuments/plumbing/double-wye-double-combo.ashx

 

[WorthFlorida]

Using a double wye in the joist you will not have enough height. If I understand your post, a new toilet will be added to the left in the same joist as the existing one. I would run a new three inch line come down if front of the existing 3" main and run it parallel toward the outside wall. Connect it somewhere before the wall. You'll need to consider the venting needs.

 

[Reach4]

Using a double wye in the joist you will not have enough height. If I understand your post, a new toilet will be added to the left in the same joist as the existing one. I would run a new three inch line come down if front of the existing 3" main and run it parallel toward the outside wall. Connect it somewhere before the wall. You'll need to consider the venting needs.

Upping the lavatory line to 2 inch and bringing it into the center input of a double wye would do the venting, right?

 

[Dan WZ]

Thanks for all the help. I have the vent already with a 2” line about 15” from the floor flange. I ordered a double wye online and I am not going to use it. I can see from one side to the other so if it lays horizontally I am pretty sure the waste will go down one side and up the other. If somehow the two toilets flush and manage to compensate for slope and distance variations then the two toilets’ output will hit and I don’t even know what happens then but I assume nothing good.

So my new plan is to put one long 90 at the start of the joist and another at the end of the joist. I should have just enough room if I start the first one as far under the joist as I can. I also plan to add a cleanout to the end of the line after I put the existing 1.5 in with a wye. It will be tight but it should work.

 

[Reach4]

Thanks for all the help. I have the vent already with a 2” line about 15” from the floor flange. I ordered a double wye online and I am not going to use it. I can see from one side to the other so if it lays horizontally I am pretty sure the waste will go down one side and up the other.

Not if the wye is fed with two 45s tilted up some.

 

[Tuttles Revenge]

You can probably see just a fraction thru the double wye.. I don't have a 3" dbl wye here, but I do have a 2" which I can see just a bit thru. That's not a deal killer. What was delivered IS what you ordered and IS the same as in the link above?

 

[Dan WZ]

All done. Is there anything I did wrong? I am concerned about the new line (from left) shown in close ups due to the backwards 45s I put in to kick it back to the long 90. Any issue or anything else anyone can see?

Thank you

Dan

 

[Dan WZ]

Here are the pictures (I didn’t burn the joist... and I know I need to support the pex line)

 

[Dan WZ]

You can probably see just a fraction thru the double wye.. I don't have a 3" dbl wye here, but I do have a 2" which I can see just a bit thru. That's not a deal killer. What was delivered IS what you ordered and IS the same as in the link above?

yeah it’s the same as a two inch one but I just don’t trust it. I only paid a few bucks for it. I’ll try to sell it on eBay or give it to Habitat for Humanity. I think I did ok with the long 90s. Thanks